Everyone has already given you the important info, I'll address a side issue: variety. I prefer to use several kinds of rations with the ratios between them depending on what I'm embarking upon.

A few MRE's, a few dehydrated, a few freeze dried, a VERY few C rations (beef stew, chicken & dumplings, etc), some D rations (chocolate bars, hard candy, etc), some prepared and unprepared foods (hard boiled eggs, baked biscuits, raw bacon, etc.), and K rations (coffee, seasonings, hot chocolate mix, tea, etc.)

I usually reserve:
The prepared stuff and K rations for breakfasts.

The MRE's or freeze dried for lunches.

C rations or dehydrated, and K rations for Suppers.

D rations are used throughout the day as you feel the need to
maintain energy levels, especially in cold weather.